Screening arrangement

ABSTRACT

A screening arrangement having a cylindrical screen and a rotor mounted interiorly thereof for directing the material to be screened toward the cylindrical screen. The screening arrangement may be disposed in a pneumatic or hydraulic conveying installation whereby the matter for screening is conveyed to the screening arrangement and the screened material and/or the residue is subsequently conveyed away for appropriate further processing.

United States Patent 1191 Link et a1.

[ Dec. 23, 1975 SCREENING ARRANGEMENT Inventors:

Assignee:

Filed:

Appl. No.:

Otmar Link, Osterburken; Rudi Baumann, Rosenberg, both of Gennany AZO-Maschinenfabrik Adolf Zimmermann, Gemiany Aug. 1, 1974 Foreign Application Priority Data Aug. 1, 1973 US. Cl. 209/250; 209/262; 209/273; 209/300 Int. CL? B07B 1/20 Field of Search 209/250, 262,270, 273, 209/284, 296, 299, 300, 304, 306; 210/360 References Cited UNITED STATES PATENTS Germany 2338909 Lauterbur 209/247 Hallam et a1. 209/141 Watson... 209/250 Staege 209/273 Turner..., 210/415 X Cram 209/273 Reddick et a1 209/250 X Irving 210/380 X Petersen 209/273 X Primary Exami'ner-Frank W. Lutter Assistant Examiner-Ralph J. Hill Attorney, Agent, or' Firm-Craig & Antonelli ABSTRACT A screening arrangement having a cylindrical screen and a rotor mounted interiorly thereof for directing the material to be screened toward the cylindrical screen. The screening arrangement may be disposed in a pneumatic or, hydraulic conveying installation whereby the matter for screening is conveyed to the screening arrangement and the screened material and- /or the residue is subsequently conveyed away for appropriate further processing.

27 Claims, 2 Drawing Figures US. Patent Dec. 23, 1975 Sheetl0f2 3,928,188

US. Patent Dec. 23, 1975 Sheet 2 of2 3,928,188

SCREENING ARRANGEMENT The present invention relates to a screening machine having a cylindrical screen and a rotor rotating in the interior of the screen, which rotor throws the material for screening upwards. The screeningmachine being arranged in a pneumatic or hydraulic conveying installation which brings in the material for screening and conveys the screen through-pass or residue away.

It is known to feed such screening machines in the usual way by introducing the material for the screening into an inlet aperture. Conventionally, there is connected to the inlet aperture a screw conveyor which transports the material to be screened into the interior of the cylindrical screen where in it is engaged by the rotor and thrown against the cylindrical screen. The material which passes through the cylindrical screen, or screen through-pass, usually falls by gravitational force out of the screening machine and passes on to further use. The screen residue or oversize material is dis charged at the open end of the cylindrical screen and also conventionally falls out by gravitational force. It is desirable to be able to use a screening machine of the kind referred to hereinabove within a continuously operating installation, for example, a pneumatic conveying installation. Conventional screening machines in pneumatic installations usually include a conveying conduit for transporting the material for screening into a conventional inlet aperture arranged at the periphery, whereas the screen through-pass is taken up, for example, at the periphery of the cylindrical screen and fed through a conveying conduit connected to additional means for further processing, for example, a separator.

Prior art screening arrangements, for example, German Pat. No. 867,193, requires a considerable amount of power for the conveying installation, since the material to be screened is introduced at the periphery and is then made to change direction through 90 into the cylindrical screen and it is conveyed substantially along the entire rotating rotor, which, of course, involves a very considerable pressure loss. Therefore, this known machine may only be used in very small conveying installations with short conveying paths. It has been attempted to overcome this disadvantage by arranging additional fan wheels directly within the screening machine but this, of course, involves a corresponding financial outlay and the constructional outlay of this machine and also the space it requires are both considerable.

The present invention has for its object to provide a compact screening machine which is intended for use in a pneumatic conveying installation and which has only a small power loss in the conveying operation and which is simple in construction.

The object is achieved according to the present invention in that the rotor is constructed so as to leave the axial internal space free, the conveying conduit for the material for screening being taken from the discharge end into the internal space. Thus, according to the present invention, the material for screening is introduced directly in the axial direction without any change of direction being required within the screening machine itself. Owing to this straight introduction of the conveying conduit, there are also substantially no sealing problems. The material for screening'passes directly the path of movement of the rotor and is thrown thereby against the cylindrical screen. The interior of the cylindrical screen arrangement of the present invention is provided only with necessary inserts, namely, the rotating rotor parts, but not with a throughshaft or the like as in the case of the prior art screening machines.

ln'other prior art screening machines, the driving motor is arranged at one end and at the opposite end thereof an attachment or extension is provided for discharging the screen residue. With this kind of screening machine, according to the present invention, the screening material conveying conduit is taken through the discharge extension into the interior. The screening material, conveying conduit is preferably made to project approximately to the central region of the rotor so that the screening material is distributed in a satisfactory manner in the interior. In known screening machines, the screening material and the coarse material moving towards the discharge extension moves in the same direction; however, in the machine constructed according to the present invention, the movements are in opposite direction with the results that the operating effect is much better due to the fact that a kind of counter-current separation is superimposed on the screening operation. Thus, according to the present invention, a particularly advantageous effect is obtained as compared with prior art machines.

In an advantageous constructional example of the present invention, the rotor comprises two or more strips or blades which are at parallel distances from the rotor axis. In order to leave the internal space free, the blades preferably are fixed on a driving disc arranged on the shaft of the driving motor, and connected to one another by a hollow cylindrical support which surrounds the screening material conveying conduit and is at least partly apertured. The support gives the blades the necessary shape-retaining ability and torsional strength but, at the same time, because of the apertures provided in it, permits the material to pass through toward the cylindrical screen.

In a particularly simple arrangement according to the present invention, the hollow cylindrical support may consist of a wire helix, for example, a helical spring with the blades being fixed to the turns of the helix. This arrangement provides a simple solution from the manufacturing and assembly points of view, for the problem of providing a hollow cylindrical support which at the same time is apertured.

The rotor of the present invention is also preferably only mounted at the driving side so that in contrast to conventional screening machines, there is no need for a further housing bearing in the region of the discharge side for the screen residue.

Finally, the blades may be slightly twisted relative to the rotor axis in order, for example, to obtain an additional conveying effect towards the discharge end.

Further features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which shows for the purposes of illustration only, one embodiment of a screening arrangement in accordance with the present invention, and wherein:

FIG. 1 is a schematic representation of a pneumatic conveying installation with a screening arrangement according to the present invention disposed therein; and 1 FIG. 2 is a partial cross-sectional view of an axial section of the screening machine in accordance with 3 the present invention.

Referring now to the drawing wherein like reference numerals are used throughout the two views to designate like parts, and more particularly to FIG. 1 which diagrammatically shows a pneumatic conveying installation comprising a storage bin 1, in which, for example, the material for screening is stored. From this storage container the material for screening is taken in a conventional manner through a duct 2, for example, by a suction effect. The necessary negative pressure is produced, for example, by a fan 3. The material to be screened passes through the conveying conduit 4 into a screening machine 5 in which certain constituents or fractions of material are to be screened. The screen residue is obtained at a discharge extension 6 whereas the screen through-pass which is to be processed further is removed by suction at the peripheral side by way of a hopper 7 through a conveying conduit 8. The screen through-pass moves, for example, into a weighing container 9 constructed as a separator having a purified air side connected to the suction fan 3, whereby the container 9 collects the material separated from the conveying flow. From the container 9 the material required, or when the desired quantity is achieved, by meansof a gate 10.

FIG. 2 shows the screening machine 5 of the present invention on a somewhat larger scale. As shown in FIG. 2, the machine comprises a cylindrical screen 11 in the interior of which a rotor 12 rotates. The rotor 12 comprisestwo or more blades 13. As shown in FIG. 2 the screening machine includes three axial 'parallel blades which are secured at one end to a disc 14 mounted on the shaft 16 of adriving motor 15.,

At the end of the screening machine'S remote from the driving motor 15, the conveying conduit 4, which brings material for screening to the screening machine 5, is taken into the screening machine 5.- The conduit 4 extends through the discharge extension 6 and projects approximately as far as the middle region of the cylindrical screen 11. In order to make this arrangement possible, the blades are secured to a hollow cylindrical support which, as shown in FIG. 2, is formed of a helical spring 17 to the turns of which the blades 13 are secured. As shown at the upper blade of FIG. 2 each of the blades 13 may be slightly twisted about the rotor axis so as to transport the material or coarse material. towards the discharge extension 6 in opposition to the direction of inflow, for example. The full-line arrows'in FIG. 2 indicate the direction of air flow, whereas the dot-dash line arrows indicate the movement of the coarse material. I a

The material for screening passing into the interior of the cylindrical screen 11 is engaged by the blades 13 and thrown towards said screen. All particles the size of which is less than the mesh width of the cylindrical screen pass into the space outside therscre en 11 and finally into the discharge hopper 7 to which the conveying conduit 8 is connected at 18 (see FIG. 2). The residue in the cylindrical screen passes through an end discharge aperture 19 into the discharge extension 6 and is either collected there in a preferably transparent container 20 or is conveyed away immediately.

Instead of a suction conveying installation shown diagrammatically in FIG. 1 with removal by negative pressure from a storage bin 1, the material may also be supplied directly to the screening machine by a gravity feed system which, in that case, in contrast to conventional machines, is arranged on the conveying conduit t 4 directly in front of the point where it enters the screening machine 5. It is also possible to insert the machine in a pressure-conveying installation; that is to say, an installation wherein, for example, the material is fed into the conveying conduit 4 between a pressure fan and the screening machine 5, either by gravitational force, an ejector effect or the like. In this case, the storage bin 1 will usually be provided at the discharge air lock.

The screening machine of the present invention may also be arranged in a hydraulic-conveying flow, for separating a liquid and a solid substance, or for separating solid substance, or for separating solid substances of differnt size. In both cases, practical experiments show that the material obtained at the discharge extension 6 is substantially dry, since the screening machine acts additionally as a centrifuge drier.

An enhanced separating effect as compared with conventional machines may also be obtained if material for screening is introduced through the conveying conduit 4 into the machine mechanically, for example, by means of a screw.

While we have shown and described a preferred embodiment of the present invention, it is understood that the same is not limited thereto but is susceptible of numerous changes and modifications as known to a person skilled in the art, and we therefore do not wish to be limited to the details shown and described herein but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.

We claim:

1. A material screening arrangement comprising: a cylindrical screen means, a rotor means disposed interiorly of said cylindrical screen means for directing material to be screened in a radially outward direction toward said cylindrical screen means, said rotor means including an axially extending internal free space for receiving the material to be screened, means for pneumatically conveying the material to be screened, a conveying conduit means for connecting the pneumatic conveying means with said internal free space, driving means disposed at one end of said rotor means for driving said rotor means, a discharge means for receiving the residue of the material to be screened, said discharge means being disposed at the end of said rotor means opposite said driving means, said conveying conduit means extending through said discharge means into said internal free space.

2. An arrangement according to claim 1, wherein said conveying conduit means extends substantially into a central area of said internal free space.

3. An arrangement according to claim 2, wherein said rotor means includes a plurality of blades, and means for mounting said blades to extend substantially parallel to the axis of said rotor means and spaced from said cylindrical screen means.

4. An arrangement according to claim 3, wherein said means for mounting said plurality of blades includes a driving disc connected to said driving means, and a hollow cylindrical support means surrounding at least a portion of said conduit means. i

5. An arrangement according to claim 4, wherein said driving means includes a drive motor and a drive shaft, and wherein said driving disc is mounted on said drive shaft.

6. An arrangement according to claim 5, wherein said hollow cylindrical support means is at least partially apertured.

7. An arrangement according to claim 6, wherein said hollow cylindrical support means is constituted by a helical spring means, said plurality of blades being fixed to the turns of said helical spring means.

8. An arrangement according to claim 7, wherein said rotor means is mounted in said cylindrical screen means solely at said driving means.

9. An arrangement according to claim 8, wherein each of said blades is slightly twisted about the axis of said rotor means.

10. A material screening arrangement comprising: a cylindrical screen means, a rotor means disposed interiorly of said cylindrical screen means for directing material to be screened in a radially outward direction toward said cylindrical screen means, said rotor means including an axially extending internal free space for receiving the material to be screened, means for conveying the material to be screened into said internal free space, driving means for driving said rotor 'means disposed at one end of said rotor means, a discharge means for receiving the residue of the material to bescreened, said discharge means being disposed at the end of said rotor means opposite said driving means, and said means for conveying the material to be screened includes a conveying conduit means, said conveying conduit means extending through said discharge means into said internal free space.

11. An arrangement according to claim 10, wherein said means for conveying the material to be screened includes a conveying conduit means extending substantially into a central area of said internal space.

12. An arrangement according to claim 10, wherein said rotor means in mounted in said cylindrical screen means solely at said driving means.

13. An arrangement according to claim 10, wherein said rotor means includes a plurality of blades, and means for mounting said blades to extend substantially parallel to the axis of said rotor means and spaced from said cylindrical screen means, each of said blades being slightly twisted about the axis of said rotor means.

14. A material screening arrangement comprising: a cylindrical screen means, a rotor means disposed interiorly of said cylindrical screen means for directing material to be screened in a radially outward direction toward said cylindrical screen means, said rotor means including an axially extending internal free space for receiving the material to be screened, means for conveying the material to be screened into said internal free space including a conveying conduit means extending substantially into a central area of said internal free space, driving means for driving said rotor means disposed at one end of said rotor means, a discharge means for receiving the residue of the material to be screened, said discharge means being disposed at the end of said rotor means opposite said driving means, said conveying conduit means extending through said discharge means into said internal free space.

15. An arrangement according to claim 14, wherein said rotor means includes a plurality of blades, and means for mounting said blades to extend substantially parallel to the axis of said rotor means and spaced from said cylindrical screen means.

16. An arrangement according to claim 15, wherein said means for mounting said plurality of blade includes a driving disc connected to said driving means, and a hollow cylindrical support means surrounding at least a portion of said conveying conduit means.

17. An arrangement according to claim 16, wherein said hollow cylindrical support means is at least partially apertured.

18. An arrangement according to claim 16, wherein said hollow cylindrical support means is constituted by a helical spring means, said plurality of blades being fixed to the turns of said helical spring means.

19. A material screening arrangement comprising: a cylindrical screen means, a rotor means disposed interiorly of said cylindrical screen means for directing material to be screened in a radially outward direction toward said cylindrical screen means, said rotor means including an axially extending internal free space for receiving the material to be screened, means for hydraulically conveying the material to be screened, a conveying conduit means for connecting said hydraulic conveying means to said internal free space, driving means for driving said rotor means disposed at one end of said rotor means, discharge means for receiving the residue of material to be screened, said discharge means being disposed at the end of said rotor means opposite said driving means, said conveying conduit means extending through said discharge means into said internal free space.

20. An arrangement according to. claim 19, wherein said conveying conduit means extends substantially into a central area of said internal free space,

21. An arrangement according to claim 20, wherein said rotor means includes a plurality of blades, and means for mounting said blades to extend substantially parallel to the axis of said rotor means and spaced from said cylindrical screen means.

22. An arrangement according to claim 21, wherein said means for mounting said plurality of blades includes a driving disc connected to said driving means, and a hollow cylindrical support means surrounding at least a portion of said conveying conduit means.

23. An arrangement according to claim 22, wherein said driving means includes a drive motor anda drive shaft, and wherein said driving disc is mounted on said drive shaft.

24. An arrangement according to claim 23, wherein said hollow cylindrical support means is at least partially apertured.

25. An arrangement according to claim 24, wherein said hollow cylindrical support means is constituted by a helical spring means, said plurality of blades being fixed to the turns of said helical spring means.

26. An arrangement according to claim 25, wherein said rotor means is mounted in said cylindrical screen means solely at said driving means.

27. An arrangement according to claim 26, wherein each of said blades is slightly twisted about the axis of said rotor means. 

1. A MATERIAL SCREEINING ARRANGEMENT COMPRISING: A CYLINDRICAL SCREEN MEANS, A ROTOR MEANS DISPOSED INTERIORLY OF SAID CYLINDRICAL SCREEN MEANS FOR DIRECTING MATERIAL TO BE SCREENED IN A RADIALLY OUTWARD DIRECTION TOWARD SAID CYLINDRICAL SCREEN MEANS, SAID ROTOR MEANS INCLUDING AN AXIALLY EXTENDING INTERNAL FREE SPACE FOR RECEIVING THE MATERIAL TO BE SCREENED, MEANS FOR PNEUMATICALLY CONVEYING THE MATERIAL TO BE SCREENED, A CONVEYING CONDUIT MEANS FOR CONNECTING THE PNEUMATIC CONVEYING MEANS WITH SAID INTERNAL FREE SPACE, DRIVING MEANS DISPOSED AT ONE END OF SAID ROTOR MEANS DRIVING SAID ROTOR MEANS, A DISCHARGE MEANS FOR RECEIVING THE RESIDUE OF THE MATERIAL TO BE SCREENED, SAID DISCHARGE MEANS BEING DISPOSED AT THE END OF SAID ROTOR MEANS OPPOSITE SAID DRIVING MEANS, SAID CONVEYING CONDUIT MEANS EXTENDING THROUGH SAID DISCHARGE MEANS INTO SAID INTERNAL FREE SPACE.
 2. An arrangement according to claim 1, wherein said conveying conduit means extends substantially into a central area of said internal free space.
 3. An arrangement according to claim 2, wherein said rotor means includes a plurality of blades, and means for mounting said blades to extend substantially parallel to the axis of said rotor means and spaced from said cylindrical screen means.
 4. An arrangement according to claim 3, wherein said means for mounting said plurality of blades includes a driving disc connected to said driving means, and a hollow cylindrical support means surrounding at least a portion of said conduit means.
 5. An arrangement according to claim 4, wherein said driving means includes a drive motor and a drive shaft, and wherein said driving disc is mounted on said drive shaft.
 6. An arrangement according to claim 5, wherein said hollow cylindrical support means is at least partially apertured.
 7. An arrangement according to claim 6, wherein said hollow cylindrical support means is constituted by a helical spring means, said plurality of blades being fixed to the turns of said helical spring means.
 8. An arrangement according to claim 7, wherein said rotor means is mounted in said cylindrical screen means solely at said driving means.
 9. An arrangement according to claim 8, wherein each of said blades is slightly twisted about the axis of said rotor means.
 10. A material screening arrangement comprising: a cylindrical screen means, a rotor means disposed interiorly of said cylindrical screen means for directing material to be screened in a radially outward direction toward said cylindrical screen means, said rotor means including an axially extending internal free space for receiving the material to be screened, means for conveying the material to be screened into said internal free space, driving means for driving said rotor means disposed at one end of said rotor means, a discharge means for receiving the residue of the material to be screened, said discharge means being disposed at the end of said rotor means opposite said driving means, and said means for conveying the material to be screened includes a conveying conduit means, said conveying conduit means extending through said discharge means into said internal free space.
 11. An arrangement according to claim 10, wherein said means for conveying the material to be screened includes a conveying conduit means extending substantially into a central area of said internal space.
 12. An arrangement according to claim 10, wherein said rotor means in mounted in said cylindrical screen means solely at said driving means.
 13. An arrangement according to claim 10, wherein said rotor means includes a plurality of blades, and means for mounting said blades to extend substantially parallel to the axis of said rotor means and spaced from said cylindrical screen means, each of said blades being slightly twisted about the axis of said rotor means.
 14. A material screening arrangement comprising: a cylindrical screen means, a rotor means disposed interiorly of said cylindrical screen means for directing material to be screened in a radially outward direction toward said cylindrical screen means, said rotor means including an axially extending internal free space for receiving the material to be screened, means for conveying the material to be screened into said internal free space including a conveying conduit means extending substantially into a central area of said internal free space, driving means for driving said rotor means disposed at one end of said rotor means, a discharge means for receiving the residue of the material to be screened, said discharge means being disposed at the end of said rotor means opposite said driving means, said conveying conduit means extending through said discharge means into said internal free space.
 15. An arrangement according to claim 14, wherein said rotor means includes a plurality of blades, and means for mounting said blades to extend substantially parallel to the axis of said rotor means and spaced from said cylindrical screen means.
 16. An arrangement according to claim 15, wherein said means for mounting said plurality of blade includes a driving disc connected to said driving means, and a hollow cylindrical support means surrounding at least a portion of said conveying conduit means.
 17. An arrangement according to claim 16, wherein said hollow cylindrical support means is at least partially apertured.
 18. An arrangement according to claim 16, wherein said hollow cylindrical support means is constituted by a helical spring means, said plurality of blades being fixed to the turns of said helical spring means.
 19. A material screening arrangement comprising: a cylindrical screen means, a rotor means disposed interiorly of said cylindrical screen means for directing material to be screened in a radially outward direction toward said cylindrical screen means, said rotor means including an axially extending internal free space for receiving the material to be screened, means for hydraulically conveying the material to be screened, a conveying conduit means for connecting said hydraulic conveying means to said internal free space, driving means for driving said rotor means disposed at one end of said rotor means, discharge means for receiving the residue of material to be screened, said discharge means being disposed at the end of said rotor means opposite said driving means, said conveying conduit means extending through said discharge means into said internal free space.
 20. An arrangement according to claim 19, wherein said conveying conduit means extends substantially into a central area of said internal free space.
 21. An arrangement according to claim 20, wherein said rotor means includes a plurality of blades, and means for mounting said blades to extend substantially parallel to the axis of said rotor means and spaced from said cylindrical screen means.
 22. An arrangement according to claim 21, wherein said means for mounting said plurality of blades includes a driving disc connected to said driving means, and a hollow cylindrical support means surrounding at least a portion of said conveying conduit means.
 23. An arrangement according to claim 22, wherein said driving means includes a drive motor and a drive shaft, and wherein said driving disc is mounted on said drive shaft.
 24. An arrangement according to claim 23, wherein said hollow cylindrical support means is at least partially apertured.
 25. An arrangement according to claim 24, wherein said hollow cylindrical support means is constituted by a helical spring means, said plurality of blades being fixed to the turns of said helical spring means.
 26. An arrangement according to claim 25, wherein said rotor means is mounted in said cylindrical screen means solely at said driving means.
 27. An arrangement according to claim 26, wherein each of said blades is slightly twisted about the axis of said rotor means. 